The present invention relates to door system for passenger transit vehicles for covering and uncovering an aperture disposed within a sidewall of the transit vehicle for the ingress and egress of passengers through said aperture. More particularly, the present invention pertains to a door operator disposed within said door system having a load bearing and guiding combination element supporting the weight of the door(s) while enabling movement thereof with minimal friction.
The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
Door systems for covering and uncovering an aperture disposed within a side wall of the transit vehicle are well know in the art of the passenger transit vehicle. As core elements, they comprise at least one door, at least one door operator attached to the structure of the passenger transit vehicle and connected to said at least one door, and a door support and guiding means connected to said at least one door for enabling the movement thereof in the opening and closing direction for at least partially uncovering and covering said aperture. The door support and guiding means are typically attached to the car structure but preferably are integral with the door operator. These door support and guiding means are also commonly referred to as a door hanger by those skilled in the art. Typically, the door hanger is used either in combination with a single door or a dual door configuration by containing a plurality of the guiding elements. From this point forward, a background discussion will be concerned with single door in combination with a single door hanger.
As stated above, the door hanger performs two main functions. The first function is related to support of the weight of the door and, therefore, support elements substantially attached to said door are disposed within said door hanger. These support elements, commonly referred to as door brackets or hanger brackets, are attached to the door with a well-known hardware elements.
The second function is related to enablement of the door movement when the prime mover disposed within door operator is energized and, therefore, guiding elements enabling movement of said door over a predetermined distance within said aperture are disposed within said door hanger.
It is generally well known in the passenger transit vehicle art to employ a door hanger having a hanger bracket encased around a substantially cylindrical hanger rod and further having a well-known recirculating linear ball bearing type disposed within the hanger bracket substantially engaging the hanger rod for linear movement thereof. The door hanger of type is disclosed in U.S. Pat. No. 6,032,416. Generally, the linear hanger rod is manufactured from a steel substrate and tempered to provide a predetermined surface hardness to prevent said surface of being damaged by the substantially cylindrical steel ball elements disposed within the interior cavity of said linear bearings. This combination requires the presence of lubricant generally applied to the surface of the hanger rod to reduce friction and component wear to an acceptable level for proper door operation. This type of door hanger is therefore susceptible to dirt and contamination present in the transit vehicle environment and requires frequent cleaning and lubricant replenishment to maintain desired level of friction and prevent premature component degradation due to wear. A linear bearing using a special seal to guard against contaminants is also well known in the art, however, the use of the seal increase friction of the door system requiring a larger prime mover to be employed in the door operator mechanism. The need for lubricant does not cooperate well with the latest trends in the art to employ a lubrication free door systems to substantially reduce the required periodic maintenance to clean and re-lubricate this type of door hangers. Furthermore, said linear bearings types cannot tolerate significant bending of the hanger rod caused by transversal or side loads due to the weight of the door and requires both the proper selection of the hanger rod size and placement of the hanger rod supports within the transit vehicle structure. And finally, the door hanger utilizing recirculating linear ball bearing and linear hanger rod is more expensive than the other type of door hangers, thus impacting the competitiveness of the overall door system.
A door hanger of a roller type disclosed in U.S. Pat. No. 6,094,867 overcomes the lubrication issue. A hanger bracket disclosed therein is affixed to the upper end of a door and connected to the drive mechanism. The door hanger bracket further includes at least two sets of longitudinally disposed vertically oriented pairs of cylindrically concave plastic rollers. The aforementioned vertical orientation provides upper and lower rollers in each pair. In operation, the upper and lower door hanger rollers cooperate with corresponding services in the semi-cylindrical hanger portion of the overhead mounted base plate, thereby providing low friction contamination resistant movement of the door panel when the rotary prime mover is energized and rotates the helical drive member. The upper rollers are generally substantially attached to the bracket and carry the weight of the door. The lower rollers generally incorporate adjustment features to provide proper running clearances with the semi-cylindrical hanger portion. The combination provides reciprocal travel of the attached door on the hanger portion of the base plate. Those skilled in the art will readily see that substantially vertical disposition of the rollers requires a car structure design of a similar vertically disposed type. This type of a car structure design is not available in all instances. Furthermore, the lower rollers are subject to inadvertent mis-adjustment creating either higher friction, if the rollers are over-adjusted in the upward direction, or unreliable motion if the rollers are over-adjusted in the downward direction.
A variation of this type of door hanger employs at least one single roller trolley assembly moving inside the hanger element having a cross-section similar to a letter xe2x80x9cCxe2x80x9d of the English alphabet. This type of door hanger generally requires complex linkage to provide interface with the drive system since the drive system is generally offset from the roller trolley assembly. It is generally preferable that this single roller trolley comprises two roller for equal weight distribution since the usage of the additional rollers may not result in equal weight distribution due to the manufacturing tolerances. As the result, the rollers and, more particularly the bearings disposed within these rollers must be of a sufficient size to assure proper load bearing capabilities.
It can be seen from the above discussion that there is a need for a reliable door hanger for transit vehicle, which substantially eliminates the need for lubricants and occupies a limited cross-sectional envelope of the vehicle structure. An additional need is to integrate load bearing hanger system with the drive system to both support the door and move it with minimal friction and at the required velocity while simplifying the interface between those two systems.
A substantial amount of transit vehicles manufactured during 1960s and 1970s employ independent door hanger and drive systems, wherein the drive system is located in the side wall of the transit vehicle or under a seat, while the door hanger is located overhead and attached directly to the car structure. Furthermore, the earlier door hanger designs employ circular ball of a bearing quality disposed within steel rails. This type of door hangers requires periodic lubrication and is extremely inefficient and exhibiting a high friction when there is a lack of such lubrication. There is a need for lubrication free door hanger capable of replacement the existing independent hanger of the old type.
The present invention provides a door operator having a door hanger comprising a pair of double trolley assemblies disposed for linear movement within a hanger rail, wherein each trolley assembly further comprises two rollers mounted substantially opposite one another and engaging roller cavities within said hanger rail. Said door hanger is integrated with the drive system as described in the preferred embodiment or is mounted independently of the drive system for replacement of the door hanger of the prior art or in new applications requiring such independency between the door hanger and drive system.
The hanger rail is manufactured from an aluminum extrusion and hard anodized to prevent wear of the roller cavities upon engagement with the double trolley assemblies. The hanger rail further incorporates mounting provisions for the drive system members as well as for mounting to the transit vehicle structure.
Either a driving or driven trolley assembly contains two rollers attached to a trolley housing with retaining rings. The rollers are manufactured form self-lubricating nylon material providing low-friction operation as well as providing for lubrication free operation in combination with the hard anodized surface of the hanger rail. The rollers can either have a convex or concave outer surface cooperating with concave or convex roller cavities respectively disposed within hanger rail.
Each double trolley is attached to the door with a hanger bracket further providing rotational constraint of the drive nut when applied in the integrated mode.
The use of double trolleys enables equal door weight distribution to each roller eliminating the need for roller adjustment.
The door hanger can be also mounted independently of the drive system allowing replacement of the independent door hangers of the old type, while cooperating with the drive system of the old type, typically mounted in the side wall of the transit vehicle or under a seat of said transit vehicle.
It is, therefore, one of a primary objects of the present invention is to provide a door hanger system substantially eliminating the need for lubrication.
Another object of the present invention is to provide a door hanger system which minimizes friction forces during door movement.
A further object of the present invention is to provide a simplified interface between a door hanger system and a drive system.
Yet a further object of the present invention is to provide a door hanger system integrated with the drive system.
An additional object of the present invention is to provide reliable door hanger system.
In addition to the objects and advantages listed above, various other objectives and advantages of the invention will become more readily apparent to persons skilled in the relevant art from a reading of the detailed description section of this document. The other objects and advantages will become particularly apparent when the detailed description is considered along with the drawings and claims, if any, presented herein.